In refineries and solids-handling systems, there is a need for a slide valve which can operate with fully reversing pressures in high pressure, high temperature erosive solid or fluid systems, which has readily removable wear-prone components, externally setable and non-changing clearances without the necessity of removing the valve from the line. Some valves in use today provide none of the above features, while others are removable with some difficulty and may be resetable externally but in operations their settings can change. In addition, slide valves currently in use have separate discs and guides with the guides bolted in the body and with clearances that can and do change.